1. Department of Obstetrics and Gynecology, Korea University Ansan Hospital, 123, Jeokgeum-ro, Danwon-gu, Ansan-si 15355, Gyeonggi-do, Republic of Korea
2. Department of Obstetrics and Gynecology, School of Medicine, Kangwon National University, 156, Baengnyeong-ro, Chuncheon-si 24289, Gangwon-do, Republic of Korea
3. Department of Obstetrics and Gynecology, Korea University Anam Hospital, 73, Goryeodae-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
4. Department of Obstetrics and Gynecology, Korea University Guro Hospital, 148, Gurodong-ro, Guro-gu, Seoul 08308, Republic of Korea